1. Field of the Invention
The present invention relates to a display system and driving method thereof, and more particularly, to a display system and driving method that are capable of descending only the output color level of red signals.
2. Related Art
Generally, a user may view directly by eyes the displayed information on a liquid crystal display. In certain special situations, such as military-use, security-monitoring, hunting, observation of a biological environment at night and etc., the brightness of the liquid crystal display has to be descended to avoid affecting the surroundings. Yet the descended brightness is too low for the user to view the liquid crystal display by eyes directly. Therefore the user has to use a night-vision device to read on the information displayed on the liquid crystal display, such as graphs, characters, images and etc. However, for a common night-vision device with the second or third generation of image intensifier, the gains of the visible light in the red and infrared fields are much greater than in other fields of wave bands. As shown in FIG. 1, even the luminance of the liquid crystal display is descended to a very low value, for a common night-vision device not designed for the purpose of viewing on the liquid crystal display, oversaturation still occurs due to an over amplification operation of the night-vision device processed on light signals. Such oversaturation causes damage of the night-vision device and over irritates the user's vision; it makes the user uncomfortable.
Technically, the overall luminance of the liquid crystal display may be descended by reducing the driving current of the liquid crystal display. Yet currently the liquid crystal display is not designed for using under an ultra low luminance. Even with a light emitting diode (LED) that has low driving current applied to the liquid crystal display as a backlight source, the liquid crystal display will then have a minimum driving current limitation since the LED has its minimum driving current limitation. If the driving current of the liquid crystal display is lower than the minimum driving current limitation, flickers of the LED will occur and cause displaying instability on the liquid crystal display. In short, by means of reducing the driving current of the liquid crystal display in the prior art, the liquid crystal display still can not provide a minimum luminance that fulfills a comfortable allowance range of human vision when viewing through a night-vision device, since a minimum luminance of the liquid crystal display is limited by driving circuits or driving components (such as LED).
In the conventional technology, when the minimum luminance of the liquid crystal display does not fulfills the allowance range of the night-vision device or human vision, the night-vision device user places a red-light optical filter sheet on the liquid crystal display, thereby makes the light passing through the red-light optical filter sheet fulfills the allowance range of the night-vision device or human vision. However, such approach has least the following three problems: (1) if liquid crystal display has a touch panel function, the optical filter sheet placed on the liquid crystal display will make the user difficult to apply touch-control operations on the liquid crystal display; (2) the user will need extra efforts to carry and protect the optical filter sheet; and (3) the optical filter sheet is costive for the user since in the market a single piece of 12.1 inch optical filter sheet will cost the user around 1000 U.S. Dollar.